Jul 28 2016

Plastics routing

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Modern plastics vary greatly throughout their manufacturing processes. The differences between various types of plastics and the different uses machinists will have for their materials cause problems for some people. A good machinist, whether you are a hobbyist or a professional, should be aware of the problems you could run into and steps you can take to get around those problems.
Not all plastics are made equal, not even plastics that share the same name when you are purchasing your raw materials. Something as simple as a change in color can alter how one plastic cuts compared to another. You need to be able to recognize and classify what kinds of categories plastic falls under when you are working with it. To start, determine whether you are working with hard or soft plastic. This is easy to determine; you can check this by seeing how rigid or flexible your material is. Alternatively you can see what type of chip is produced when the material is cut. Soft plastic chips will curl while hard plastic chips retain their solid shape. A single type of plastics is not always universally hard or soft; some plastics can be hard or soft depending on how they were manufactured. Knowing the geometry of your cutting tool is the second step to success. Tools that are best suited for cutting plastic have high rake and low clearance. These days there are thousands of different tools made for plastics cutting that you can choose from. Soft plastics tools have “O” shapes and are usually straight or spiraled in shape. Hard plastics tools can have an “O”, spiral shape or a “V”, straight shape.

Routing plastics

Routing plastics

One of the most irritating problems you can run into is the plastics material welding. This problem can happen due to the direction of your cut, using a cutting tool that is too small or having a chipload (the thickness of a chip) that is too large. Chipload is the most common cause of this problem. Your chipload is determined by your spindle speed, feed rate and the number of edges on your cutting tool. In plastic routing you want your chips to be just the right size to distribute heat correctly. Another potential problem is your finished project having poor finish. Having good finish is extremely important on plastic items, especially ones that are made to be put on display somewhere. The quality of your finish is going to be heavily affected by your chipload. Problems aside from chipload tend to come from the condition of your CNC router. You want to make sure that your CNC router is up to speed on maintenance and performance at all times. Learning to work with plastic correctly is a matter of practice and with time you will become experienced enough that you will run into these problems less and less, until you stop running into them almost altogether.
Making sure you have the right bits for plastics is one of the most important parts of preparing for projects. Your best option for hard plastics is a solid carbide router tool. If you cannot get one of those a carbide tipped tool is a good second choice but they will not perform as well as a solid carbide tool. You can use the same kind of tools on soft plastics but high speed steel tools will also work well on these softer materials. Your CNC router should be capable of speeds of at least 15,000 RPM to work on plastic. A CNC router is the best type of CNC machine for working on plastic, being the machine that is best suited for working at the high speeds your projects will require. Ideally you want to be working at 18,000 RPM, if your machine can operate at that speed, at a feed rate of 200 in. per minute. This is a general figure for plastics in general and the exact speed and feed rate you should use will vary a bit between different types of plastic.


Feb 18 2016

Plastic mold making with a hobby router

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Plastic mold making with a hobby router

Creating a plastic mold is one in all the most effective strategies for prototyping. Creating a plastic mold is simple and knowing the way to create one are often terribly handy. Mistreatment everyday objects from around your home, you’ll build a plastic vacuum molder which will alter you to try and do something from creating a brand new toy for your child to making a custom case for your latest project. The idea behind a vacuum molder is easy. Mistreatment suction from a vacuum, liquid plastic sheets are a unit tightly adhered to the item you wish a mold of, effectively making a plastic copy of the item. Typically plastic vacuum molders area unit terribly giant and really dearly-won machines except for smaller comes this DIY molder can work simply fine.

Plastic mold project

Plastic mold CNC project

For this project you wish a high, a powerful airtight box, a home appliance and 2 frames. Your high is wherever you set the item you’re repeating and it’ll would like holes trained in it for suction. The holes should be trained so the suction is consistent over the whole area of the highest. Mistreatment associate degree airtight box helps maintain consistent suction. Once choosing a vacationing, you’ll use a standard home appliance, however a store vac can work higher since they need higher suction. The frames are wont to hold the sheets of plastic; a combine of image frames can work nicely. You may conjointly would like a cutting knife or razor and an electric drill with alittle bit (a ⅛” bit could be a sensible size to use).
Building little vacuum molder are often finished a plastic paste jar (or one thing similar, as long because it is plastic therefore you’ll cut it), a 2-liter bottle, some plastic wrap and adhesive tape. For alittle model like this a daily home appliance can work fine; a store vacation isn’t necessary. The lid of your paste jar is your high therefore drill holes in it in a very grid pattern to distribute the suction equally. once that’s done cut a hole within the aspect of the paste jar that’s simply sufficiently big for the tip of your 2-liter bottle to travel through. stop|bring to a halt|interrupt} the highest of the 2-liter bottle and place it through the outlet within the jar (the end of the tip ought to air the skin of the jar). currently plastic wrap the jar (but leave the bottle tip exposed) to create it airtight and place the lid on. aside from the holes within the lid and also the hole within the 2-liter bottle tip the whole molder should be airtight.

CNC plastic molder

plastic mold project

Now your vacuum molder is prepared to be used. ensure the entire object fits on the highest with holes round the edges. don’t use objects which will soften or deform beneath heat. don’t use objects that or too tall or the plastic can stretch an excessive amount of and tear. place your object on the space and place a spacer beneath it; this may create the model look higher. Connect the hose on your vacuum to the 2-liter bottle tip. Stretch out your plastic between your frames and warmth it. will|this will|this could|this may} be finished a heat gun otherwise you can hold the plastic over a burner (do not bit the burner with the plastic directly). don’t use a gas burner; the plastic can turn. Once the plastic starts to sag within the middle, it’s hot enough for the mold. Slowly stretch the plastic over the item and acquire a decent seal around it. The plastic must be as airtight as potential for max suction. Once this is often done activate the vacuum. when the plastic has wrapped round the object flip the vacuum off and hold it in situ till it hardens and provides it time to cool down. Once it’s cool take the frames off, cut away the surplus plastic and you have got your model.
This method works with little objects however you’ll build one thing larger. If you employ an outsized bin, a baking pan, an even bigger bottle and bigger image frames you’ll do that whole method on a bigger scale. you’d most likely would like a stronger vacuum for larger molders and you’ll got to seal off it rather than simply mistreatment adhesive tape to stay everything airtight. you’ll purchase sheets of plastic on-line or probably regionally from a spread of suppliers. Along with your molder you’ll currently model expeditiously. Use some material like covering material rosin and you may have a particular copy of your object.the object turn the vacuum off and hold it in place until it hardens and give it time to cool. Once it is cool take the frames off, cut away the excess plastic and you have your model.
This process works with small objects but you can build something bigger. If you use a large trash can, a baking pan, a bigger soda bottle and larger picture frames you can do this whole process on a larger scale. You would probably need a stronger vacuum for bigger molders and you may need to caulk it instead of just using duct tape to keep everything airtight. You can purchase sheets of plastic online or possibly locally from a variety of suppliers. With your molder you can now prototype efficiently. Use some material like fiberglass resin and you will have an exact copy of your object.